Electric selective control circuit



June 2, 1.9 70 T. M. MARGESON ET AL v 3,515,391

ELECTRIC SELECTIVE CONTROL CIRCUIT Filed Aug. 15. 1968 2 Sheets-Sheet 1 l4 I6 24 26 28 3o 32 34 I I I8 I E 3 I I [f I 0' k 36 l .J

I94 2 2| o use i0 I u 4 O 32 [I $220 3 7 w I88 %96 we we [72 I74 200 I I92 fz'yj 16 -4 INVENTORS Theodore M. Margeson Hugh W. Denny June 2, 1970 T. M. MARGESON ET 3,515,891

' ELECTRIC SELECTIVE CONTROL CIRCUIT Filed Aug. 1 5. 1968' 3 Sheets-Sheet INVENTOR Theodore M. Margeson Hugh M. Denny f ,3 iironzevrs United States Patent O 3,515,891 ELECTRIC SELECTIVE CONTROL CIRCUIT Theodore M. Margeson, 3121 Piedmont Road NE., Atlanta, Ga. 30305, and Hugh W. Denny, Atlanta, Ga.; said Hugh W. Denny assignor to said Theodore Margeson, Atlanta, Ga.

Filed Aug. 15, 1968, Ser. No. 752,971 Int. Cl. B60r 25/00 US. Cl. 307- 13 Claims ABSTRACT OF THE DISCLOSURE An electric control circuit has a readily removable essential element which can be plugged in or out of the circuit as desired. The missing element is a small rugged piece which can be mounted on a key or other small support piece easily carried by the user.

SUMMARY OF THE INVENTION This application relates to electric control circuits, and particularly circuits which are controlled by insertion or removal from the circuit of an operating element.

Accordingly, it is an object of this invention to provide an electric control circuit which allows ready insertion or removal of an essential operating element.

It is a still further object of this invention to provide an electric control circuit wherein the essential operating element can easily be plugged into the circuit or removed therefrom.

It is a still further object of this invention to provide an electric control circuit adapted to operate only on receiving a given one of such essential operating elements.

It is a still further object of this invention to provide an electronic control circuit in which the essential operating element is small and readily carried by the user.

It is a still further object of this invention to provide an electronic circuit responsive only to an essential operating element which is not fragile.

It is a still further object of this invention to provide an electric control circuit which can either be activated or deactivated by insertion or removal of an accessible operating element.

It is a still further object of this invention to provide an electric control circuit, dependent upon insertion or removal of an accessible operating element, to control other electric circuits.

These and further objects and advantages of this invention will become apparent from the following description and drawings, taken together with the claims.

DESCRIPTION OF THE DRAWINGS FIG. 1 shows diagrammatically an electric control circuit which can :be used with automobile ignition systems.

FIG. 2 is a detailed illustration of the circuit of FIG. 1, showing the various components thereof.

FIGS. 3 and 4 show a key and matching socket which can be used with the circuit illustrated in FIGS. 1 and 2.

DETAILED DESCRIPTION FIGS. 1 and 2 show a special application of the electric control circuit of the subject invention as applied to automobile ignition systems. However, it should be understood that the use of an electric control circuit, the operation of which is dependent upon a small easily carried essential operating element, easily plugged into and out of circuit to control operation thereof, has many applications, and that this is only one of many such applications.

In FIG. 1, wherein the electric control circuit is applied to an automobile ignition system, battery 10 is a 12-volt conventional automobile battery which supplies power to the circuit.

A circuit closing element 12 closes the break in line 14, permitting line 14 to carry current from battery 10 to the oscillator unit 16. Conductors 18 and 20 are con nected to the oscillator unit 16 and are adapted to receive the removable crystal 22. If crystal 22 has the correct value, oscillator unit 16 will begin to function.

The oscillating signal is carried along line 24 to an amplifier unit 26. The alternating frequency is then applied to the input end of an elongated coaxial cable, permitting the signal to be carried to the remainder of the circuit which can be located some distance from the initial part of the circuit, such as the outside of the fire wall under the hood.

The alternating signal is picked up by a frequency responsive circuit 32 and passed on to an amplifier section 34 where it is amplified and subsequently rectified.

The resulting direct current is carried along lines 36 and 38 to the control gate 40 of diode 42. Diode 42 forms a direct link through line 44 between relay coil 46 and ground. Ordinarily, the diode 42 is gated open, blocking flow of current from line 14 through line 48 and relay coil 46.

When the diode 42 is gated closed by the signal received along line 38, the current passing through relay coil 46 closes relay switch 50, permitting battery current from line 14 to flow through lines 52, 54 and 56 to the auto-mobile ignition system.

FIG. 2 is a more specific showing of the circuit described in FIG. 1. The l2-volt battery 58 supplies current along lines 60 and 62, where a circuit connecting element 64, comparable to element 12 of FIG. 1, is :moved to connect poles 66 and 68 to battery 58. The l2-volt current is carried along lines 70 and 72 when this connection is made. Current is carried along line 74 to the oscillator unit of the circuit. Current passes through coil 76, and along line 78 to the collector 80 of the oscillator transistor 82. Line 84 provides bias to the base of the transistor. The emitter 86 of transistor 82 is directly connected to a plug-in piece 88, connected to one side of piezo-electric crystal 90. The other side of crystal 90 is connected to terminal 92.

The pieZo-electric crystal 90' serves as the essential operating element in the oscillator circuit. When it is plugged in, a strain is induced therein, causing it to produce an electric signal which activates the oscillator circuit.

The resonant frequency of the oscillator circuit is designed to correspond to that of the crystal. The oscillator circuits of each unit will all have different resonant frequencies, so that only the crystal having the matching resonant frequency will activate the oscillator frequency. This crystal, therefore, constitutes the essential operating element, the absence of which inactivates the entire circuit, even though current is supplied thereto.

The vibration frequency of the crystal supplied to such circuits is selected to vary over a range from one to two hundred megacycles, permitting a large number of frequency combinations.

Once the crystal 90 is plugged into the circuit at 88 and 92, the oscillator circuit begins to function and sends out a signal frequency along line 94 to the amplifier section 96. The amplified alternating frequency is coupled through the coupling network 98 to the connecting cable at 100 and carried along its length indicated in dotted line to the coaxial cable output end 102. The

a connecting cable conductor is connected to the primary coil of transformer 104, the secondary coil of which is connected to the resonant crystal 106. The resonant frequency of crystal 106 matches the output frequency as supplied by the oscillator from the secondary coil of transformer 104 which supplies alternating electrical energy to activate it. The frequency output from the resonant circuit of crystal 106 is supplied to the amplifier stage 108, where it is amplified, and subsequently coupled through transformer 110 and capacitor 112 to the diode 114 which converts the signal to DC current. The DC current from diode 14 is passed along line 116 to diode gate 118 of gated diode 120. Resistor 115 and capacitor 117 form a delay circuit to prevent unauthorized testing for the correct crystal value. The voltage supplied along line 16 to the gate 118 must be supplied for a length of time to build up to the required activating voltage. The circuit values are chosen so that only an alternating current having the frequency stability of a crystal circuit will give a suiiicient build-up to operating voltage.

On receiving the signal through gate 118 the gated diode 120 becomes conductive, allowing current to pass through relay coil 122. Current is supplied to coil 122 through lines 124 and 126, which are connected to the automobile battery 58 through line 72, switch 62, and line 60.

The current passing through coil 122 pulls in the relay switch 130, closing it, and connecting line 70 to line 132, thereby supplying 12-volt battery power to the ignition system.

FIG. 2 shows a circuit embodiment used for activating an automotive ignition system, and it should be recognized that activation of the relay coil 122 could also be used to control circuits locking the steering mechanism or the hood lock, or any other electrical or mechanical component so desired.

The system shown contemplates the use of a coaxial cable, where the signal receiving portion could be located in a different area than that of the signal generating section. As mentioned above, it is also possible to locate all component parts of this circuit with the exception of the insertion crystal contacts 88 and 92 and the electrical circuit contacts 66 and 68 in an inaccessible location to prevent bypassing of the control circuit.

In FIG. 2, the lead 150, which connects the starter solenoid to the battery 58 is also shown as part of the ignition switch circuit.

FIG. 3 illustrates a key and socket assembly which could be used with the circuits of FIGS. 1 and 2.

A key piece 160, and the elongated shank 162 has a contact plate 164 which is the equivalent of members 12 and 64 respectively of FIGS. 1 and 2. The insertion crystal element 170 is embedded within the lower portion of shank 16 2 and has protruding contacts 172 and 174.

Adjacent the head of the key piece 160, the lower surface of key shank 162, has a downwardly extending locking nub 176 immediately adjacent to a spring receiving depression 178.

The key has its shank 162 adapted to fit the socket member 180. Key shank 162 is received into the socket opening 180 to a point adjacent the end 184 thereof. In this position, contact member 164 connects the contacts of 180, 186 and 188, to supply power to the circuit. The insertion crystal contacts 172 and 174 respectively engage contacts 190 and 192. The insertion crystal 170 corresponds to the crystal 90 of FIG. 2, and the electrical contacts made at each side of the crystal by the key and socket connections are represented by points 88 and 92 of FIG. 2.

In this modification, it is contemplated that the socket 180 would contain the entire oscillator signal generating and amplifying circuit, with the receiving signal circuit being disposed at a remote location. A coaxial cable 194 shown at the rear of the socket is the equivalent of the coaxial cable shown in FIG. 2, while the electrical leads 196 and 198 correspond to electrical leads 70 and 126 of this figure.

The key member can be held in the key receiving socket by the spring member 200 which has a contour similar to that of the locking nub 176 and the spring receiving depression 178 under the lower part of key shank 172. When the locking nub 176 passes over the first curved portion of the spring, the key is held in position within recess 182 of the socket 180.

The circuit is made highly selective by choosing matched piezo-electric crystals having the same resonant frequency. Thus, hundreds of different units each operating on a different frequency are possible.

It should be noted that the oscillator control circuit used here, with the removable crystal, has a wide range of control applications. The circuit makes possible a simple key system which cannot be duplicated because of the wide range of individual crystal values that could be chosen, and the difficulty of independently determining the resonant frequency of a crystal on a given key.

It thus can. be seen that we have provided a new type of locking circuit arrangement where the essential operating element, namely a crystal which can have a large number of different values, controls operation of the circuit. The user carries this key element with him mounted on some type of support member, such as a key-type member, which plugs into the circuit to permit operation thereof.

The crystal member itself, cannot be duplicated, as could a conventional key, and the circuit cannot successfully be scanned for the correct crystal value. Remote location of the elements, also precludes the possibility of jumping a connection, which is a rather common occurrence with the ignition switches of automobiles.

With regard to automobile circuits, which is only one of many applications for this type of circuit, it is also possible to control the locking of the hood, to prevent bypassing of the circuit from the engine side of the dashboard.

It can readily be seen that there are many applications for this circuit, such as door locks, safes, night watchmen control stations, automatic admitting turnstiles, identification systems, and so forth.

Overload cut out can be placed in the receiver circuit to preclude using a powerful oscillator signal generator to overpower the crystal in the receiver.

It is also possible to use a concept of this invention in a conventional radio transmitter and receiver arrangement, rather than the direct physical conductor connection used in the disclosure.

It also should be noted that any type of circuit interrupter arrangement could be used in place of the relay 130.

The invention presupposes the use of one key frequency, but it is possible to use a number of different combined frequencies for a greater security in the circuit.

While the invention has been described, it will be understood that it is capable of further modifications and this application is intended to cover any variations, uses, or adaptations of the invention following in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains, and as may be applied to the essential features hereinbefore set forth and as fall within the scope of the invention or the limits of the appended claims.

What we claim is:

1. An electric control circuit, comprising:

(a) an electrical source;

(b) an electrically operated device to be connected in circuit with said source;

(c) electrically operated switch means connected between said source and said electrically operated device;

(d) an electrical control circuit connected with and controlling operation of said electrically operated switch means;

(e) single frequency generating means forming a first part of said electrical control circuit;

(f) single frequency matching means forming a second part of said electrical control circuit for re ceiving said single frequency and generating a con trol signal when said frequency is received;

(g) each of said frequency means includes a crystal control element for permitting precise frequency matching;

(h) one of said crystals is adapted to be physically removed from its circuit to permit activation or deactivation of the said electrical control circuit.

2. The electric control circuit as set forth in claim 1,

wherein:

(a) said frequency generating means is a crystal oscillator circuit which has a manually removable crystal element.

3. The electric control circuit as set forth in claim 2, wherein:

(a) said oscillator signal is passed through a transistor amplifier stage and a shielded conductor to said single frequency matching means.

4. The electrical control circuit as set forth in claim 3, wherein:

(a) said frequency matching means includes control signal delay circuitry for precluding scanning of the circuit for the operable frequency.

5. An electric control circuit, comprising:

(a) an electrical source;

(b) an electrical control circuit which includes an oscillator circuit for producing a control signal;

(0) electrically operated switch means connected to an electrical output line and operatively controlled by said electrical control circuit;

(d) switch means connecting said electrical source with said electrical control circuit and said electrically operated switch means;

(e) said oscillator circuit being complete with the exception of missing frequency determining element;

(f) a key receiving socket electrically connected to said switch and to said oscillator circuit, and having a first set of two contacts which form part of said switch means, and a second set of contacts for electrically plugging said missing frequency determining control element into said oscillator circuit;

(g) a key having thereon a switch closing element and said missing frequency determining element for the oscillator circuit;

(h) said first and second sets of contacts being positioned along a key receiving recess within said socket at appropriate points so that contact is made with said switch closing element and said frequency determining element on said key, when said key is inserted within said recess, whereby when said switch is closed and said missing frequency determining element is plugged into said oscillator circuit, a control signal is emitted to close said electrically operated switch means.

6. The electrical control circuit as set forth in claim 5, wherein:

(a) said missing frequency determining element is a piezoelectric crystal.

7. The electrical control circuit as set forth in claim 6, wherein:

(a) said electrically operated switch means is a relay,

and said control means is a gated diode.

8. The electric control circuit as set forth in claim 5, wherein:

(a) said control means includes a delay circuit which precludes scanning of the activating frequency range of the circuit to determine the exact operating frequency.

9. The electric control circuit as set forth in claim 5, wherein:

(a) said control circuit includes a frequency signal conducting cable; and

(b) a remotely located frequency responsive circuit which is connected to said control means.

10. The electric control circuit as set forth in claim 9, wherein:

(a) said frequency responsive circuit includes a crystal frequency determining element.

11. An electric control circuit, comprising:

(a) an electrical source;

(b) electrically operable switch means connected between said source and an electrical output line; (c) oscillator control circuit means having a readily insertable and removable frequency generating crystal element;

(d) frequency responsive means remotely located from said oscillator control circuit and connected thereto by a frequency conductor cable, said frequency responsive means including a crystal element for precisely matching the oscillator generated control frequency;

(e) control signal circuit generated means connected to said frequency responsive means and to said electrically operable switch means for producing a control signal when said frequency responsive means receives the control frequency from said oscillator control circuit;

(f) time delay means connected in circuit with said control signal means for preventing a build-up of the required control voltage for said electrically operable switch means for a desired period of time to preclude scanning of the electrical control circuit to determine the oscillator circuit frequency.

12. The electric control circuit as set forth in claim 11, wherein:

(a) said time delay circuit is an R-C network through which said control signal passes;

(b) said control circuit includes a gated diode to the gate of which said signal is applied.

13. The electric control circuit as set forth in claim 11, wherein:

(a) said electrically operable switch means is a magnetically operated switch unit having an electrical coil through which current is passed to control operation thereof.

References Cited UNITED STATES PATENTS 3,136,307 6/1964 Richard.

3,222,534 12/1965 Scott.

3,425,033 1/1969 Pfund 30710 X 3,428,033 2/1969 Watts 30710 X ROBERT K. SCHAEFER, Primary Examiner T. B. JOIKE, Assistant Examiner US. Cl. X.R. -414 

